The proposed research is concerned with the mechanism of enzymatic reactions, the mechanism of chemical reactions in aqueous solution relevant to enzymatic reactions, and the nature of noncovalent interactions in aqueous solution. Physical properties of liver esterase and succinyl CoA-acetoacetate CoA transferase will be determined, followed by further mechanistic investigation. Mechanism studies will be carried out primarily on acyl and carbonyl group transfer reactions, with special attention to the role and lifetime of a tetrahedral addition intermediate and the detailed mechanism of catalysis by general acids and bases. Activity coefficient measurements in the presence of urea and other addends will be carried out on uric acid and related compounds in a further attempt to evaluate the importance of hydrogen bonding interactions in aqueous solution.